When you start homebrewing and make some research about recipes, equipment and raw materials, you’ll find that almost everything is based on some kind of codified volume : 5 gallons. You, of course, can brew larger batches but must modify things in equipment, ingredients and methods to your brewing.
The term “lager”, like many brewing terms, comes from our German Brewing Brethren. It means “storeroom” or “warehouse”. They key reason behind the term is that lager, unlike ale, has a longer fermentation time which leads to a “cleaner” tasting beer than ales. This a basic primer on making lager beers.